The field of this invention relates to inflatable tire supporting structures and more particularly to an improved machining apparatus to assist in the manufacturing of the tire supporting structure.
It has been common practice for a number of years to mount the inflatable tire of a vehicle upon a steel rim, and then to secure the steel rim to the drum of the vehicle. Normally, such steel rims were formed as an integral unit in a rough cast form. In an effort to improve the spider section of the wheel (the section centrally located with respect to the rim), it has been common to employ the use of a hubcap which is designed to be ornamental and pleasing to the eye. A large number of different types of hubcaps of various designs have been employed in the past.
Within recent years it has been common to make ornamental the spider portion of the wheel itself, thereby eliminating the need for a hubcap. It has been found that if the spider is formed of a non-ferrous metal such as aluminum or magnesium, the spider is more receptive to styling by chrome plating than a steel spider. However, it has not been particularly easy to establish a strong, leakage free connection between the non-ferrous spider and the ferrous rim.
Most such rims are to support a tubeless tire wherein the rim must establish an airtight connection with the tire. It has been a known practice in the past to rivet the rim to the spider. As a result, it has been common that a non-perfect riveting causes the pressurized air within the tire to leak out past one or more of the rivets. Also, although a satisfactory rivet connection may be initially established, after a period of time it may loosen permitting air to leak from the tire.
In an effort to overcome the use of rivets, there have been numerous attempts as welding the spider to the rim. However, the welding of a ferrous metal to a non-ferrous metal is not easily accomplished even by the most skilled artisan. Further, the welding technique is inherently time consuming. The cost of manufacture of such wheel assemblies is substantially increased when using the welding technique.